tim/prune/load/ByteScooper.java

   1 package tim.prune.load;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5
   6 /**
   7  * Class to scoop bytes from an input stream into an array.
   8  * The size of the array doesn't have to be known in advance.
   9  * This is used for getting images and sound files out of zip
  10  * files or from remote URLs.
  11  */
  12 public class ByteScooper
  13 {
  14         /** Bucket size in bytes */
  15         private static final int BUCKET_SIZE = 5000;
  16         /** Amount by which barrel size is increased on demand */
  17         private static final int BARREL_SIZE_INCREMENT = 100000;
  18
  19         /**
  20          * Scoop bytes from the given input stream and return the result
  21          * @param inIs input stream to scoop bytes from
  22          * @return byte array
  23          */
  24         public static byte[] scoop(InputStream inIs) throws IOException
  25         {
  26                 byte[] _barrel = new byte[BARREL_SIZE_INCREMENT];
  27                 byte[] _bucket = new byte[BUCKET_SIZE];
  28                 int numBytesInBarrel = 0;
  29                 // read from stream into the bucket
  30                 int numBytesRead = inIs.read(_bucket);
  31                 while (numBytesRead >= 0)
  32                 {
  33                         // expand barrel if necessary
  34                         if ((numBytesInBarrel + numBytesRead) > _barrel.length)
  35                         {
  36                                 byte[] newBarrel = new byte[_barrel.length + BARREL_SIZE_INCREMENT];
  37                                 System.arraycopy(_barrel, 0, newBarrel, 0, numBytesInBarrel);
  38                                 _barrel = newBarrel;
  39                         }
  40                         // copy from bucket into barrel
  41                         System.arraycopy(_bucket, 0, _barrel, numBytesInBarrel, numBytesRead);
  42                         numBytesInBarrel += numBytesRead;
  43                         // read next lot from stream into the bucket
  44                         numBytesRead = inIs.read(_bucket);
  45                 }
  46                 // Now we know how many bytes there are, so crop to size
  47                 if (numBytesInBarrel == 0) return null;
  48                 byte[] result = new byte[numBytesInBarrel];
  49                 System.arraycopy(_barrel, 0, result, 0, numBytesInBarrel);
  50                 return result;
  51         }
  52 }